Frangible firing device



United States Patent ce Patented Nov. 26, 1963 URE 3. Applied to theexterior of electrically non- 3,111,901 conductive nose-cone section 10by means well known in FRANGIBLE FIRING DEVICE the art, is printedcircuit 18. This printed circuit is ap- Harold L. Dodson, King ofPrussia, and William A. Danesi, Wayne, Pa assignors to the United Statesof America as represented by the Secretary of the Army Filed Nov. 21,1960, Ser. No. 70,893 1 Claim. (Cl. I027 0.2)

This invention relates to a fuzing device for mounting on a missile andmore particularly to an electrical means printed on a frangible body fordetonating the missile warhead before warhead damage occurs as a resultof impact.

The typical fuzing system generally employs a piezoelectric crystal insuch a manner that when compressed, as by impact, an electrical impulseis generated which serves to detonate the warhead. With such devices asthese, however, the necessary electrical impulse is generated only whenthe warhead impacts the target with sufficient force to compress thepiezoelectric crystal surfaces. Accordingly, a glancing impact betweencrystal and target may be insufiicient to generate the necessarydetonating voltage. In the case of spike-type targets, it is absolutelyessential that the crystal and target meet precisely head-on, otherwisethere will be a complete failure to detonate. Additional deficiencies ofemploying piezoelectric crystals lie in their sensitivity to temperaturechanges and their ability to accumulate and retain electrical charges ontheir surfaces thereby adding to the drawbacks and inadequaciespreviously mentioned.

A surface fuzing system must supply the proper fuzing signal to thewarhead before any warhead damage occurs as a result of impact. Theultimate surface fuzing system would be one that would fuze the missileat instant of impact with the target. However, practical aspects of thissystem must include safety factor allowances for handling, shock,vibration, temperature extremes, and the like.

It is an object of this invention, therefore, to overcome theseobjectional features of the prior art and provide a fuzing system whichwill detonate the warhead almost instantly upon impact.

A further object of this invention is to provide a missile nose cone offrangible material having a printed circuit thereon, which nose conewill shatter on impact interrupting said circuit and detonate thewarhead.

These and other objects will become more apparent when reference is hadto the following detailed description and drawings in which:

FIGURE 1 illustrates an elevation of a stepped nosecone having a printedcircuit schematically shown thereon;

'FIGURE 2 illustrates a cross-sectional view taken on line 2-2 of FIGURE1;

FIGURE 3 shows a typical missile body having mounted thereon onfrangible nose-cone having a printed circuit interiorly thereof andconnected to a conventional warhead;

FIGURE 4 illustrates a cross-section of the nose-cone of FIGURE 3 takenon line 4-4 and showing the printed circuit on the interior thereof;

FIGURE 5 illustrates a nose-cone having a solid nosecone shown insection, and a frangible portion with a printed circuit immediately tothe rear of the solid section; and

FIGURE 6 schematically illustrates a typical fuzing and detonatin gcircuit.

Referring now in more detail to the drawings and particularly to FIGURES1 and 2 thereof, there is shown a stepped, resinous nose-cone section 10of thermosetting plastic or other frangible, electrically non-conductivematerial, having a substantial ring portion 12 with a plurality ofequally spaced mounting holes 14 for attaching to a conventional missilebody 16, typically shown in FIG- plied in a pattern such that maximumcoverage over the entire nose-cone section is obtained. The ends ofprinted circuit 18 terminate in connections 2% which extend through tothe interior of nose-cone section '10 for connection to a warheadsection 11 schematically shown in FIGURE 3.

In operation, the circuit 18 may be energized at or before missilelaunching. However, on impact with a target, the resinous nose-cone,because of its brittle character, will shatter, thereby interrupting theenergized printed circuit causing the warhead to detonate. The circuitschematically illustrated in FIGURE 6 shows, by way of example, only atypical arrangement for accomplishing the detonation, wherein suchcircuit comprises a source of potential P, a switch S which is closedjust prior to launching, a resistor R, a gas-filled diode D, and warheadE. Short-circuit xy depicts what in actuality is printed circuit 18whereby at launching and prior to impact only that portion of thecircuit comprised of P, S, R, x, and y is energized. At impact, x-ybecomes interrupted thereby allowing electrical flow from R to D and Eresulting in the det-onating of the warhead. The time which elapsesbetween circuit rupture and detonation amounts to only a fewmilli-seconds; consequently the distance which the warhead continues totravel toward the target during this brief interval is insufficient todo any damage to the warhead portion. By proper design of the nose cone,shattering of this component can be predicted for high or low velocityimpacts.

FIGURE 4 illustrates a modification of the preferred embodiment of thisinvention wherein the printed circuit portion 18a of the fuze circuitryis placed on the interior surface of a nose-cone portion 102:: so as toadequately cover the entire expected target contact area of thenosecone. Circuit connections 20a extend through the nosecone body fromthe interior to the exterior surface for suitable connections theretoand to facilitate the required missile check-out procedure prior tolaunching.

FIGURE 5 is a further modification illustrating a nosecone sectionhaving a solid tip portion 22 with a frangible section 2'4 immediatelyrearward thereof, the frangible portion having a printed circuit 18b onits surface terminating in connections Ztlb. As shown in FIGURE 5, thenose cone is connected to the missile body 24 by circumferential means26. Any target impact forward of connection 26 will cause shattering ofthe nosepone thus producing the switch opening necessary to generate apulse to initiate a firing train.

Thus, it is now readily apparent that by fitting an electrical circuiton a frangible missile component of dielectric material, and locatingthis component so as to impact with a target with sufiicient force tofracture the material and interrupt the printed circuit, a fuz-ing pulsecan be generated to detonate the warhead almost instantly. Byfabricating the frangible component from a resinous material, standardtechniques of applying printed circuits can be readily utilized withease and economy.

This invention is not limited to nose-cone applications, however, butmay be employed on any portion of a missile body and the resinousmaterial need not necessarily rupture completely, but just enough tointerrupt the electrical continuity of the printed circuit on itssurface.

Having particularly described our invention, it is obvious that manymodifications and variations may be re sorted to by those skilled in theart without departing from the scope of the appended claim.

We claim:

A surface fuz-ing device for a missile having a warhead and a detonatingcircuit for said warhead, said fuzing References Cited in the file ofthis patent UNITED STATES PATENTS Winkley June 3-0, 1925 Bleakney et a1July 12, 1955 Ward May 28, 1958 Perret May 19, 1959 FOREIGN PATENTSGreat Britain Oct. 2, 1957

